The present invention pertains to a vehicle impact sensor. More particularly, the present invention pertains to an impact sensor adaptable for use with a vehicle to detect impact with an obstacle during backing up of the vehicle before damage occurs.
Ever since vehicles have been equipped with means for driving in reverse, there has been an ever-present source of damage or injury when backing up the vehicle. This is due to the fact that vehicles are designed primarily to be driven forward. Thus, the driver has very limited vision of obstacles present when backing up and, in addition, control of the vehicle during backing up is severely limited. In an attempt to alleviate the difficulties of backing up a vehicle, mirrors, such as side view mirrors and rear view mirrors, have been incorporated into the design of vehicles to facilitate the driver's visual perception of obstacles behind the vehicle during backup. However, the use of such mirrors is extremely inadequate because oftentimes the obstacle simply is not in the optical line of sight of the mirrors. Many factors contribute to the limitation of the use of mirrors for visual perception of rearward obstacles. For example, many times such obstacles are below the trunk line of the car and thus the trunk blocks the obstacle from view. Furthermore, the practical design of many vehicles inherently limits any view of such rearward obstacles from the driver even if mirrors are used.
In particular, the practical design of trucks requires a relatively long cargo area positioned behind the driver and usually consists of an opaque steel box-like structure or an opaque tank. Further, recreational vehicles, such as mobile homes and the like, are configured such that it is extremely difficult for the driver to see obstacles when backing up. Also, drivers of recreational vehicles are often inexperienced with regards to driving a large long vehicle. Obviously, it is therefore impossible for the driver of such trucks and recreational vehicles to adequately perceive rearward obstacles when backing up even if multiple mirrors are used.
Thus, truck drivers have great difficulty when backing up their vehicles and often back over or into obstacles behind the truck causing great damage to the obstacle, such as a car or building, and to the truck. Furthermore, because of the relatively great distance between the rear of the truck and the driver, as well as the particularly, noisy environment caused by the truck's diesel engine, the driver often cannot know that he has made contact with a rearward obstacle and will continue backing up even after hitting such an obstacle causing further damage. In addition, trucks are usually equipped with very powerful engines, required due to the great weight of the truck and the anticipated weight of its payload. Therefore, when backing up the driver of the truck will usually not notice the slight hesitation of the momentum of the backing up truck when an obstacle is encountered. Usually, when such contact is made, the driver does not "feel," hear, or see that contact has been made with the rearward obstacle until much damage has occurred.
There have been attempts to provide devices for warning a driver of a rearward obstacle during back up. Such devices, typically, attempt to warn the driver before substantial damage occurs due to contact with the obstacle. These devices include closed circuit television monitors in which a television camera is mounted at a suitable location at that back of the vehicle and a monitor is placed where the driver can view the scene behind the vehicle when backing up. Such a device is very cost prohibitive and it is extremely difficult for the driver to control his vehicle when backing up and looking at the monitor. Another example of such a warning device is a radar or infrared system in which a radar or infrared unit is disposed at the rear of the vehicle and determines the proximity of rearward obstacles using radar or infrared. When an obstacle is detected that is within a certain "danger zone" during backing up, the driver receives a signal warning him of the existence of the obstacle. However, false signals are apt to occur, especially in parking lots, at red-lights or stop signs due to the proximity of other vehicles. Also, such systems do not warn the driver of obstacles which are not directly behind the vehicle. Further, such systems are also very expensive and require complicated electronic and mechanical components.
There have been attempts to provide devices which sense contact with an obstacle during backing up of a vehicle before substantial damage occurs. U.S. Pat. No. 4,967,180 issued to Wang discloses probes extending from the rear corner of a vehicle at an angle and designed to improve on the infrared system and contact with an unseen obstacle during backing up of the vehicle. This system signals the driver that when contact has been made between the probe and the obstacle before the vehicle actually makes contact and substantial damage occurs. However, such prior attempts utilizing probes are extremely inadequate and prone to many design flaws. For example, usually such probes are placed at strategic locations at the rear of the vehicle where it is anticipated that the probe will contact an obstacle before the vehicle does. However, such probes do not provide any way to protect the entire rear of the vehicle because unless the obstacle happens to hit the probe, before the vehicle, the driver will never receive the intended warning. Also, such probes are unsightly and inconsistent with the external appearance of the vehicle.